Methods of manufacturing integrated circuit devices having contact holes using multiple insulating layers
The present invention provides methods of forming contact holes and integrated circuit devices having the same. A conductive plug is formed on a substrate. A first insulating layer is formed on the conductive plug and a second insulating layer is formed on the first insulating layer. The second insulating layer is etched to expose at least a portion of the first insulating layer and the first insulating layer is etched to expose at least a portion of the conductive plug.
Latest Samsung Electronics Patents:
- Display device packaging box
- Ink composition, light-emitting apparatus using ink composition, and method of manufacturing light-emitting apparatus
- Method and apparatus for performing random access procedure
- Method and apparatus for random access using PRACH in multi-dimensional structure in wireless communication system
- Method and apparatus for covering a fifth generation (5G) communication system for supporting higher data rates beyond a fourth generation (4G)
This application is a divisional application of co-pending U.S. patent application Ser. No. 10/241,026 entitled Methods of Forming Contact Holes Using Multiple Insulating Layers, filed Sep. 11, 2002, which claims priority from Korean Application No. 2001-0055810, filed Sep. 11, 2001, the disclosures of which are hereby incorporated herein by reference as if set forth in their entirety.
FIELD OF THE INVENTIONThe present invention relates to methods of forming integrated circuit devices and, more particularly, to methods of forming contact holes and integrated circuit devices having the same.
BACKGROUND OF THE INVENTIONAs integrated circuit devices become more highly integrated the fabrication process of these devices may become more difficult. For example, because the devices themselves have decreased in size, the space between the electrical wires in these devices as well as the width of the electrical wires themselves may decrease in size. Accordingly, contact holes that are formed between these wires have also been influenced, for example, contact holes may have a decreased diameter and/or increased depth. Contact holes of this nature are difficult to manufacture.
Contact holes having narrow diameters and increased depths, present in, for example, dynamic random access memory (DRAM) cells, may be formed using a self-aligned contact method. Typically, methods employing a self-aligned contact method do not require alignment of an etching mask. Further, using a self-aligned contact method may enable the manufacture of smaller contact holes without an additional alignment margin.
According to conventional methods of forming self-aligned contact holes, a plurality of first patterns are formed on the integrated circuit substrate. The first pattern typically includes a conductive layer pattern and a silicon nitride layer pattern formed on the conductive layer pattern. A nitride spacer is formed on a sidewall of the first pattern. An insulating layer is formed on the resulting structure by depositing silicon oxide on the surface of the resulting structure. A photoresist pattern is formed to expose portions of the first patterns. The insulating layer is anisotropically etched using the photoresist pattern as an etching mask to form a contact hole exposing a surface of the substrate between the first patterns.
According to conventional methods, depositing a conductive material in a contact hole may be difficult because the already small diameter of the hole may be decreased even further by the presence of a nitride spacer formed on the sidewall of the first pattern. One solution to this problem is to reduce the thickness of the nitride spacer to make room for the conductive material. However, reducing the thickness of the spacer such that there is space for the conductive material, may cause an electrical short to occur between the conductive layer pattern and conductive material deposited in the contact hole. This type of short is typically referred to as the bridge phenomenon and it typically occurs when the nitride spacer is too thin and, thus, etched through during subsequent etching processes.
Furthermore, since the spacer includes silicon nitride which has a dielectric constant of more than about 7 and the dielectric constant of an oxide layer has a dielectric constant of about 3.9, the parasitic capacitance of the first pattern may increase. When the parasitic capacitance increases, the response speed of the integrated circuit device may decrease during the operation thereof.
Solutions to the above identified problems with conventional fabrication methods have been attempted. For example, Japanese Patent Application Publication No. 11-168199 discusses a method wherein the contact hole is formed first and a spacer is formed on the inner side surface of the contact hole.
The method of manufacturing a DRAM discussed in the above referenced Japanese Patent Application will be discussed below with respect to
Referring now to
Referring now to
Referring now to FIG 1C, a spacer 22 is formed on a sidewall of the first contact hole 20. In particular, a silicon oxide layer is deposited on the third insulating layer 18 and in the first contact hole 20 (FIG. 1B). The silicon oxide layer is anisotropically etched to form a spacer 22 on the sidewalls of the first contact hole 20.
Referring now to
According to conventional methods of fabricating DRAMs discussed above, the area of the bottom of the first contact hole 20 is enlarged because the first contact hole 20 is formed prior to the formation of the spacer 22. In addition, the parasitic capacitance of the conductive pattern decreases since the spacer 22 is formed using silicon oxide.
However, when the contact hole 20 is small in diameter and/or deep, the conventional methods may present a problem. For example, since the storage electrode 24 has a stacked shape, enlargement of an area of the storage electrode 24 is limited and, therefore, a capacitance of the capacitor may decrease. Furthermore, if the sidewall of the first contact hole 20 is formed to have a step, the silicon oxide layer may not be deposited uniformly, which may result in the bridge phenomenon between the conductive pattern 14 and the storage electrode 24.
In the above-mentioned fabrication methods of DRAM, one or more cylindrical storage nodes may be formed so as to enlarge the surface area of the storage electrode 24.
Now referring to
However, if the second contact hole 44 is formed without being precisely aligned with the conductive plug 40 disposed below the second contact hole 44, the oxide layer 42 may be over etched and the spacer 12 disposed on the side of the conductive pattern 14 may be accidentally etched away as illustrated by the broken lines in FIG. 2B. The spacer 12 may be accidentally etched because the spacer 22 and the oxide layer 40 have similar etching rates. Accordingly, a pattern bridge (an electrical connection) may occur between the conductive pattern 14 (functioning as bit line) and the storage electrode 48 and the integrated circuit device may not function correctly or at all.
SUMMARY OF THE INVENTIONEmbodiments of the present invention provide methods of forming contact holes and integrated circuit devices having the same. Methods according to embodiments of the present invention include forming a conductive plug on a substrate. A first insulating layer is formed on the conductive plug and a second insulating layer is formed on the first insulating layer. The second insulating layer is etched to expose at least a portion of the first insulating layer and the first insulating layer is etched to expose at least a portion of the conductive plug.
In some embodiments of the present invention, the second insulating layer is preferentially etched with respect to the first insulating layer and the first insulating layer is preferentially etched with respect to the second insulating layer and the conductive plug. The second insulating layer may be thicker than the first insulating layer. The first insulating layer may have a thickness of from about 30 to about 150 Å.
In further embodiments of the present invention, the process of forming a conductive plug includes forming a first conductive layer on the substrate and forming a third insulating layer on the first conductive layer. The first conductive layer and the third insulating layer may define a contact hole. A spacer is formed on the sidewalls of the first conductive layer and the third insulating layer and a conductive material may be deposited in the second contact hole to form the conductive plug.
In still further embodiments of the present invention the process of forming the first conductive layer may include forming a barrier metal layer on the substrate and forming a metal layer on the barrier metal layer. The barrier metal layer may include titanium and/or titanium nitride and the metal layer may include tungsten. A width of the first conductive layer may be smaller than a width of the third insulating layer.
The present invention now will be described more fully with reference to the accompanying drawings, in which embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the concept of the invention to those skilled in the art. In the drawings, when an element is referred to as being “connected” or “coupled” to another element, it can be directly connected or coupled to the other element or intervening elements may be present. In contrast, when an element is referred to as being “directly connected” or “directly coupled” to another element, there are no intervening elements present. It will also be understood that when a layer is referred to as being “on” another layer or substrate, it can be directly on the other layer or substrate, or intervening layers may also be present. Like reference numerals refer to like elements throughout.
Embodiments of the present invention will be described with respect to
Referring now to
A photoresist film is deposited on the first insulating layer using, for example, a spin-coating method. The photoresist film is partially removed using, for example, a photo process to form a photoresist pattern. The first insulating layer, the metal layer and the barrier metal layer are sequentially etched using the photresist pattern as an etching mask to form each of the first patterns 56. As illustrated in
The first conductive layer pattern 52 may be formed to have a width that is smaller than the width of the first insulating layer pattern, as illustrated in FIG. 3A. In particular, the first insulating layer pattern 54 may be formed by ansiotropically etching the first insulating layer. The first insulating layer pattern 54 may be etched by adjusting the etchant of the metal layer disposed under the first insulating layer pattern 54 such that the lower sides of the first insulating layer pattern 54 are under-cut. Accordingly, a metal layer pattern 52b may be formed having a smaller width than that of the first insulating layer pattern 54 by from about 10 to about 100 Å.
Similarly, the etchant of the barrier metal layer may be adjusted such that the barrier metal layer pattern 52a has a smaller width than the first insulating layer pattern 54 by from about 10 to about 100 Å. Accordingly, the width of the metal layer pattern 52b may be substantially similar to the width of the barrier metal layer pattern 52a.
Referring now to
In particular, the spacer 58 may be formed by depositing a silicon oxide layer on the surface of the integrated circuit substrate 50 and the surface/sidewalls of the first patterns 56. The silicon oxide layer is anisotropically etched to form the spacer 58 on the sidewalls of the first patterns 56 as illustrated in FIG. 3B. The silicon oxide layer is deposited at a temperature of about `400° C. or less to prevent the first conductive layer pattern 52 from being oxidized. Furthermore, the silicon oxide layer deposited on the sidewalls of the first patterns 56 typically has a sufficient and uniform deposition thickness and a good step coverage of the silicon oxide layer. The silicon oxide layer on the sidewalls of the first patterns 56 is deposited, for example, using catalytic atomic layer deposition (CALD).
Although a particular method of fabricating the spacer 58 is discussed above, the present invention is not limited to this process. The spacer 58 may be formed by another method without departing from the teachings of the present invention. For example, a silicon oxide layer may be deposited having a sufficient thickness such that each of the first patterns 56 are covered by the silicon oxide layer. The silicon oxide layer may then be etched to form a contact hole exposing a side of each of the first patterns 56 and a surface of the integrated circuit substrate 50.
A photoresist pattern perpendicular to the first patterns 56 may be formed on the first patterns 56 and the silicon oxide layer. The silicon oxide layer may be etched using the first patterns 56 and the photoresist pattern as an etching mask, such that a contact hole is formed between the first patterns 56. The spacer 58 may be formed on the sidewall of the contact hole.
Referring now to
Referring to
Referring to
Referring to
As illustrated in
Accordingly, when the second insulating layer 64 is etched to form the contact hole 68, the first stopping layer 62 may only be etched to the extent that the second insulating layer 64 is over etched because the etching selectivity of the first stopping layer 62 and the second insulating layer 64 is so large. Therefore, the second insulating layer 64 may be etched to expose the first stopping layer 62 and the exposed first stopping layer 62 may be etched to expose at least a portion of the conductive plug 60. Furthermore, even though a photo-misalign may be generated during the etching of the second insulating layer 64, the spacer 58 disposed on the sidewall of the first patterns 56 may not be etched since the first stopping layer 62 reduces the likelihood that the spacer 58 will be etched. Accordingly, a process failure resulting from an over etching of the spacer 58, for example, the generation of a pattern bridge between the first patterns 56 and the conductive plug 60, is less likely to occur.
Embodiments of the present invention will now be discussed with respect to
Referring now to
In particular, an isolation oxide layer 102 is formed on the integrated circuit substrate 100 using an isolation process, such as a shallow trench isolation (STI) process to define an active area 101 in the integrated circuit substrate 100. The MOS transistor is formed on the active area 101 of the integrated circuit device 100.
In particular, a thin gate oxide layer 202 is formed on a surface of the active area 101 using a thermal oxidation method. A gate electrode 203 of the MOS transistor is formed on a surface of the gate oxide layer 202 that functions as a word line.
The gate electrode 203 may have a polycide structure including, for example, a polysiliconlayer and a tungsten poly silicide layer that are sequentially stacked on each other. The polysiliconlayer is doped with high-density impurities using a conventional doping process, such as a diffusing process, an ion implanting process, and/or an in-situ doping process. Further, a silicon nitride layer pattern 204 is formed on the gate electrode 203. A spacer 206, including, for example, silicon nitride, is formed on each sidewall of both the gate electrode 203 and the silicon nitride layer pattern 204. Impurities are implanted into the integrated circuit substrate 100 to form source/drain regions 205a, 205b of the MOS transistor on a surface of the active area 101. One of the source/drain regions, i.e. a doping area, is a capacitor contact area with which the storage electrode of the capacitor makes contact. The other of the source/drain regions is a bit line contact area with which the bit line makes contact. In some embodiments of the present invention, the source region 205a is the capacitor contact area, and the drain region 205b is the bit line contact area. In further embodiments the source/drain regions are reversed.
An insulating layer 103 including, for example, an oxide, such as borophosphosilicate glass (BPSG), is formed on the surface of the integrated circuit substrate 100 including the MOS transistor. The insulating layer is planarized by, for example, a chemical-mechanical polishing (CMP) process. The silicon nitride pattern layer 204 may function as a CMP stopper. The insulating layer 103 is etched with a high etching selectivity with respect to the silicon nitride pattern layer 204, such that a contact hole self-aligned with the gate electrode 203 is formed.
The polysilicon layer doped with the high-density impurities is deposited in the contact hole. The polysilicon layer is etched to expose the silicon nitride layer 204. Thus, the first pad electrode 104a and the second pad electrode 104b are formed in the contact hole, the first pad electrode 104a making contact with the source region 205a and the second pad electrode 104b making contact with the drain region 205b.
Referring now to
The bit line conductive layer 108 is deposited on the insulating interlayer 105 and in the bit line contact hole 111. The bit line conductive layer 108 may be formed to have, for example, a composite layer structure including, for example, a metal and a metallic compound. In some embodiments of the present invention, the bit line conductive layer 108 includes a barrier metal layer 106 including, for example, Ti/TiN, and a metal layer 107 including, for example, tungsten. The barrier metal layer 106 may reduce the likelihood that the metal layer is lifted and that the resistance of the metal layer will increase during subsequent thermal processes. A first insulating layer 110 is deposited on the bit line conductive layer 108. The first insulating layer 110 may be a single layer including, for example, silicon nitride based material, or a composite layer including, for example, silicon oxide based material and silicon nitride based material.
The first insulating layer 110 may protect the bit line during subsequent etching processes to form the self-aligned contact hole. In some embodiments of the present invention, the double-layered bit line conductive layer 108 is formed to make direct contact with the bit line contact hole 111. Alternatively, the bit line conductive layer 108 may be formed to directly make contact with a bit line plug after forming the bit line plug in the bit line contact hole 111.
Now referring to
Referring now to
The bit line conductive layer pattern 108a may be formed to have a smaller width than that of the first insulating layer pattern 110a by, for example, adjusting the etchant of the bit line conductive layer 108. In addition, an anti-reflection layer (not shown) may be formed on the first insulating layer 110 before the first photoresist pattern is formed to improve the performance of the photolithography process. In some embodiments of the present invention, the anti-reflection layer may be formed as a single layer of, for example, silicon oxynitride (SiON), or as a composite layer of, for example, a thermal silicon oxide layer and a silicon oxynitride (SiON) layer. The anti-reflection layer may reduce the likelihood that a light scattering will occur on a lower substrate during subsequent photolithography processes.
Referring now to
On the other hand, when the bit line conductive layer pattern 108a includes tungsten, a deposition of the second insulating layer 116 can cause the tungsten to oxidize. In particular, when the second insulating layer 116 is deposited at high temperature or with an oxide layer requiring high-temperature deposition process or high-temperature baking process, such as, for example, BPSG or spin-on-glass (SOG) film, side surfaces of the bit line conductive layer pattern 108a may be exposed and, thus, the tungsten of the bit line conductive layer pattern 108a may be oxidized. Oxidization of the tungsten may cause a lifting defect of the bit line conductive layer pattern 108a, i.e. the bit line conductive layer pattern 108a may be lifted due to a volume expansion of the tungsten. Accordingly, in some embodiments of the present invention, the second insulating layer 116 is deposited using, for example, a high-density plasma (HDP) process so as to reduce the likelihood of the occurrence of the above-mentioned tungsten oxidization. The HDP can be performed at a low temperature of about 400° C. or less without a producing a void.
A surface of the second insulating layer 116 is planarized using, for example, a CMP process using the fist insulating layer pattern 110a as a CMP stopper. In embodiments of the present invention that include the formation of the anti-reflection layer on the second insulating layer 116, the anti-reflection layer may be used as the CMP stopper instead of the first insulating layer pattern. Furthermore, the CMP process may be carried out so as to expose only a portion of the first insulating layer pattern 110a or to fully expose the first insulating layer pattern 110a.
Now referring to
The second insulating layer 116 and the insulating interlayer 105 are sequentially etched through the second photoresist pattern 117 with high etching selectivity with respect to the first insulting layer pattern 110a, such that the first pad electrode 104a is at least partially exposed. A high oxide-to-nitride layer selectivity can be applied since the spacer is not formed on the sidewalls of the bit line structures 113. Accordingly, the storage node contact hole 118 which is self-aligned with respect to the bit line structures 113, is formed. In embodiments of the present invention wherein the first insulating pattern layer 110a is wider than that of the bit line conductive layer pattern 108a, residue of the second insulating layer 116 remains on the sidewall of the bit line structures 113 in the storage node contact hole 118. The residue typically has a thickness corresponding to a width difference between the first insulating layer pattern 110a and the bit line conductive layer pattern 108a.
Now referring to
The third insulating layer may be deposited without oxidizing the bit line conductive layer pattern 108a exposed in the storage node contact hole 118. Thus, the third insulating layer may include, for example, oxide material deposited at a low temperature that has a good step coverage and may be deposited using a liquid phase deposition (LPD) process or catalytic atomic layer deposition (CALD) process.
Referring now to
Referring now to
Referring now to
Due to the thickness of the fourth and fifth insulating layers 126, 130, a storage node contact hole making contact with the capacitor electrode layer 122 may not be uniformly formed. Accordingly, the second stopping layer 128 may be formed between the fourth insulating layer 126 and the fifth insulating layer 130. The fourth insulating layer 126 may be formed to have a thickness of from about 2,000 to about 4,000 Å to allow the etching depth to be controlled during a successive anisotropical etching process. Furthermore, although the fifth insulating layer 130 is etched with high etching selectivity with respect to the second stopping layer 128, the second stopping layer 128 may be partially etched at such a portion that an etching rate is relatively high. Therefore, the second stopping layer 128 is formed such that it is thick enough so as not to be completely removed during the etching process of the fifth insulating layer 130. The second stopping layer 128 may be formed to have a thickness of from about 500 to about 1,000 Å.
Referring now to
The fourth insulating layer 126 is formed to be relatively thin, for example, having a thickness of from about 2,000 to about 4,000 Å. An etching rate of the fifth insulating layer 130 is typically relatively uniform, so that the contact hole may be formed to have precise and uniform depth. Therefore, the fourth insulating layer 126 may be accurately etched to expose the first stopping layer 124.
Referring now to
According to embodiments of the present invention, the first stopping layer 124 is provided, and the fourth insulating layer 126 is etched using an etchant having a high etching selectivity with respect to the first stopping layer 124. Accordingly, the first stopping layer 124 is hardly etched during the etching the fourth insulating layer 126. Consequently, although a photo misalign may be generated between the contact hole 134 and the capacitor electrode layer 112, the spacer 120 may not be etched.
Referring now to
As described above with respect to
In the drawings and specification, there have been disclosed typical preferred embodiments of the invention and, although specific terms are employed, they are used in a generic and descriptive sense only and not for purposes of limitation, the scope of the invention being set forth in the following claims.
Claims
1. A method of manufacturing an integrated circuit device comprising the steps of:
- i) forming a plurality of bit line structures on an integrated circuit substrate, each of said bit line structures including a first conductive layer pattern and a first insulating layer pattern stacked on said integrated circuit substrate;
- ii) forming a first insulating layer on a surface of the integrated circuit substrate, a sidewall and a surface of the bit line structures;
- iii) partially etching said first insulating layer using said first insulating layer pattern as an etching mask to thereby form a storage node contact hole exposing a surface of said integrated circuit substrate corresponding to a position between said bit line structures;
- iv) forming a conductive plug type storage electrode in said storage node contact hole, the conductive plug type storage electrode including a first conductive material;
- v) forming a first stopping layer on an upper surface of said bit line structures and said storage electrode;
- vi) forming a second insulating layer on said first stopping layer;
- vii) forming a contact hole exposing a lower electrode by sequentially etching a portion of said second insulating layer and said first stopping layer; and
- viii) forming a storage node making contact with said storage electrode in said contact hole with a second conductive material.
2. The method of claim 1, wherein forming a conductive plug is preceded by forming a spacer on sidewalls of said storage node contact hole.
3. The method of claim 2, wherein said spacer formed on the sidewall of the storage node contact hole comprises a silicon oxide based material.
4. The method of claim 1, wherein said first stopping layer comprises a silicon nitride layer.
5. The method of claim 1, wherein said first stopping layer is formed to have a thickness of from about 30 to about 150 Å.
6. The method of claim 1, wherein said portion of said first stopping layer is etched via a post-etch treatment for removing residue of said second insulating layer.
7. A method of manufacturing an integrated circuit device comprising the steps of:
- i) forming a plurality of bit line structures on an integrated circuit substrate, each of said bit line structures including a first conductive layer pattern and a first insulating layer pattern stacked on said integrated circuit substrate;
- ii) forming a first insulating layer on a surface of the integrated circuit substrate, a sidewall and a surface of the bit line structures;
- iii) partially etching said first insulating layer using said first insulating layer pattern as an etching mask to thereby form a storage node contact hole exposing a surface of said integrated circuit substrate corresponding to a position between said bit line structures;
- iv) forming a conductive plug type storage electrode in said storage node contact hole, the conductive plug type storage electrode including a first conductive material;
- v) forming a first stopping layer on an upper surface of said bit line structures and said storage electrode;
- vi) forming a second insulating layer on said first stopping layer;
- vii) forming a contact hole exposing a lower electrode by seqiuentially etching a portion of said second insulating layer and said first stopping layer; and
- viii) forming a storage node making contact with said storage electrode in said contact hole with a second conductive material, wherein forming a storage node comprises:
- i) forming a polysilicon layer in said contact hole with polysilicon material and sequentially depositing said polysilicon material on an upper surface of said second insulating layer;
- ii) isolating said storage node by polishing a surface of said polysilicon layer formed on said second insulating layer; and
- iii) removing said second insulating layer.
8. A method of manufacturing an integrated circuit device comprising the steps of:
- i) forming a plurality of bit line structures on an integrated circuit substrate, each of said bit line structures including a first conductive layer pattern and a first insulating layer pattern stacked on said integrated circuit substrate;
- ii) forming a first insulating layer on a surface of the integrated circuit substrate, a sidewall and a surface of the bit line structures;
- iii) partially etching said first insulating layer using said first insulating layer pattern as an etching mask to thereby form a storage node contact hole exposing a surface of said integrated circuit substrate corresponding to a position between said bit line structures;
- iv) forming a conductive plug type storage electrode in said storage node contact hole, the conductive plug type storage electrode including a first conductive material;
- v) forming a first stopping layer on an under surface of said bit line structures and said storage electrode;
- vi) forming a second insulating layer on said first stopping layer;
- vii) forming a contact hole exposing a lower electrode by sequentially etching a portion of said second insulating layer and said first stopping layer, wherein said portion of said first stopping layer is etched via a post-etch treatment for removing residue of said second insulating layer;
- viii) forming a storage node making contact with said storage electrode in said contact hole with a second conductive material; and
- ix) forming a second stopping layer on a lower surface of said second insulating layer, wherein said second insulating layer is partially etched out such a way that residue of said second insulating layer remains on said first stopping layer.
9. The method of claim 1, wherein forming a storage node comprises:
- i) forming a polysilicon layer in said contact hole with polysilicon material and sequentially depositing said polysilicon material on an upper surface of said second insulating layer;
- ii) isolating said storage node by polishing a surface of said polysilicon layer formed on said second insulating layer; and
- iii) removing said second insulating layer.
10. The method of claim 6, further comprising forming a second stopping layer on a lower surface of said second insulating layer, wherein said second insulating layer is partially etched out such a way that residue of said second insulating layer remains on said first stopping layer.
Type: Grant
Filed: Jun 9, 2004
Date of Patent: May 24, 2005
Patent Publication Number: 20040224454
Assignee: Samsung Electronics Co., Ltd.
Inventors: Beom-Jun Jin (Seoul), Young-Pil Kim (Gyeonggi-do)
Primary Examiner: Phuc T. Dang
Attorney: Myers Bigel Sibley & Sajovec, P.A.
Application Number: 10/864,277